Device for regulating the pitch of variable pitch propellers during flight



nsvlca son an NOV. 13, 1934. E UET 1,980,847 GULATING m3 PITCH or VARIABLE PITCH PROPBLLERS DURING FLIGH'f A 4 Shets-Sheet 1 Filed Sept. 30. 1931 Nov. 13, 1934. L. BREGUET 1,930,847 ARIABLE PITCH PROPELLERS DURING FLIGHT 4 Sheets-Sheet 2 DEVICE EOE BEGULATING THE PITCH OP V Filed Sept. 50.1951

Nov. 13, 1934. L. BREGUET 1,930,347

mmca FOR nseumnue rm: 'rrrca 0P vmmm rmcn rnoranmans mmme FLIGHT Filed Sept. 30, 1931 4 Sheets-Sheet s Patented Nov. 13, 1934 UNITED STATES eAT 1,980,847 ENT. OFFICE DEVICE FOR REGULATING THE PITCHIOFQ VARIABLE PITCH PROPELLEBS DURING FLIGHT Louis Brguet,

Paris, France, assignor to Societe' Anonyme Des Ateliers DAviatlon Louis Breguet, Paris, France, a company of France Application September 30, 1931, Serial In France June 16, 1931 8 Claims. (c1. rid-163) In the French Patent No. 697,692, 'iiled June 19, 1930, and granted November 4, 1930, there is described a device for automatically adjusting the pitch of variable pitch propellers and of revolving wings in which the variation of the pitch is obtained through a regulating mechanism constructed and operating so that the angle of incidence of the'propeller blades isa function of the ratio 17/0 of the traction T exerted by the propeller on the driving shaft to the driving couple or resistance couple C of the propeller. For instance, said mechanism may be so devised that the propeller hub is mounted so as to be able to slide and to rotate on the driving shaft and is connected to this shaft through a cable, a connecting rod, or a roller guided by a rail of suitable outline, the variations of relative position of the propeller shaft and of the hub being transmitted to the propeller by a suitable transmission mechanism. Said transmission mechanism may for instance consist of an arm, fixed on the driving shaft, the end of which is adapted to be displaced by a cam of suitable outline, secured to the pro- I peller blade the angle of incidence of which is be adjusted. I 4

My present invention relates, in a general way, to all devices for automatically regulating the pitch of propellers, but more particularly to .devices of the type described in the above mentioned French'patent. r 4

The object of my invention is toprovide improvements in the devices for regulating the pitchof propellers with a view to reducing thestresses to which the hub and the controlling gear are sub-' jected, and: therefore, to reducing their weight, the space they occupy, and also their wear and tear.

' also increase the sensitiveness of the automatic control mechanism and moreover they allow the pilot to interfere personally, either to assist and complete the action of the automatic control mechanism (which may then be considered as .a servo-motor), or to modify, within determined limits, the position of equilibrium automatically are fltted'in a rotatable manner; I

The traction produced by the component, along the axis of 'revolutionof the blades about themselves, of the centrifugal force acting upon said blades;' 1

The torsion produced by the centrifugal torque vided with a The improvements according to my invention 7 the; ball bearings, and

which acts upon the blade, .said centrifugal torque acting in a direction tending to reduce the pitch;

The improvements according to the'present invention make it possible to reduce or balance these stresses, to control the position of equilibrium of theblades, and finally allow, as above stated, the pilot to interfere personally in order to modify the working of the device.

Said improvements consist:

1. In disposing the bearings in which each pro- I peller blade is fitted on either side of the" axis of revolution of the propeller, as opposed to what exists in the usual arrangementlwhich, in particular is described in theFrench patent above referred to) andin which said bearings are both located on the same side of the axis of the driving shaft. Each blade isscrewed on a sleeve proprolonged piece extending beyond the axis of the driving shaft, and fitted in the opposite blade, the whole of the two blades then acting as a continuous beam. That arrangement has the advantage of reducing the stress resulting from the traction exerted on the outer bearing traction and of the reaction of the inner bearing as in the usual arrangement. Furthermore as the reaction of the outer bearings is equalto the quotient of the driving torque divided by the distance between the bearings, the increase of said distance substantially reduces thejvalue of said reaction. I

2. In disposing the outer bearing of one blade nd the inner bearing of the opposite blade in the same plane so as to reduce to a minimum the stresses to'which they are subjected, and therefore their dimensions and the friction due to the rotation of the blades when the pitch is varied.

3. In balancing directly thecentrifu'gal efforts of of. a single thrust piecelocated in the central part 'of the mechanism and which accordingly is'not not only the centrifugal force of the blade itselfbut also that due to the weights of the sleeve, of

ofthe roller track of thrust piece which is integral with the blade, The

fact of placing a. single thrust piece at-the center I of the mechanism, together with the above' described disposition of the bearings, reduces to agreat 'extent'the stresses to which said thrustpiece is subjected. Said thrust piece is only subjected to the centrifugal force due to the blade one blade by ,those of the'other'blade, by'means the' 11 5 itself, or rather to a portion of that force, owing E9 .3? p ovision of the balancing device which jected to the centrifugal force.

' are utilized, varies in be hereinafter described. Furthermore, whereas, in the case of two thrust pieces, the reaction of each blade was transmitted to the other blade through the medium of the hub casing, in the present arrangement the reaction of one blade is exerted directly on the other, and the casing has no action to perform, which makes it possible to reduce its weight.

4. In balancing, either wholly or partly, each blade taken separately by a fixed weight located in the prolonged part of said blade and on the opposite side of the axis of the blade proper. The passive resistances exerted on the thrust piece are thus reduced.

5. In balancing the centrifugal torque of eac blade by means of a compensating weight which is inserted tangentially between said blade and.

the prolonged part of the opposite blade.

It is known that the centrifugal force exerted on one blade can be split up intoa force parallel to the axis of said blade, and which is absorbed by the thrust piece, and a torque which tends to reduce the pitch and which, within the limits that the same direction as the pitch. In order to make possible the controlling of the pitch, each blade must be balanced as regards the centrifugal torque, which may be obtained by means of two balancing weights, identical and working simultaneously. Said weights have a certain stroke and are necessarily sub- Each of them i annular and slides, without any relative angula displacement, along, and inside of, the sleeve of one blade. the prolonged part of the opposite blade and creates a torque equal and opposite in direction to the half centrifugal torque of said blade.

6. In providing transmission means connected to the hub and serving on the one hand to indicate to the pilot for each position of equilibrium of said propeller,

and on the other hand to allow the pilot to control during the flight the variation of the pitch in order, either to help the working of the automatic control arrangement, which then acts as a kind of servo-motor, or to modify, within certain limits, the law of variation of the pitch that corresponds to the controlling system that has been adopted, and, in particular in the case of the above mentioned French patent, the law of variation of the pitch that corresponds to the shape of the cams that-serve to connect the propeller hub to the blades.

In one particular embodiment of said transmission means it is possible to provide a sumciently loose coupling so that the propeller hub will move freely and-the action imparted by the pilot will has been purposely provided willhave been taken up.

A preferred embodiment of my inven ion w ll be hereinafter described with reference to the appended drawings, ample, and in which:

Fig. 1 is a plan view removed;

. Fig. 2 is a sectional view on the Fig. 1; Fig. 3 is a sectional view on the line 3-3 of Fig. 2;

Fig. 4 is a perspective view, partly in section. of the device for balancing the centrifugal torque, in which the fixed weight disposed in the progiven merely by way of exof the hub, the blades being line 2-2 of longed piece of the blade has not been shown for the sake of simplicity;

. the usual means.

the driving shaft from It is inserted between said sleeve and 1 the value of the propeller pitch bearings of. one blade.

be transmitted only when the play that 'tures, as shown in Fig. 5 is a diagram showing how'the forces are through a plate 2 to which it is secured by means of bolts in the proper axial position, said plate in turn being connected to driving shaftl through The above mentioned mechanism essentially comprises: a frame such as 4, rigidly secured to plate 2, a hub casing 5 enclosing the mechanism proper and adapted to both slide in a frontward direction along the driving shaft and rotate about said shaft; finally rotatable propeller blades and their accessories, which follow the displacementsof the casing andare further capable of being given a rotary-displacement for varying the incidence.

I Small connecting rods 3, jointed to frame 4 through ball and socket joints provided with ball bearings transmit the driving torque to the casing of hub'5 through lugs such as 6 (Fig. 1). They also transmit the traction exerted by the propeller to frame 4 and driving shaft 1 and take a posi-. tion of equilibrium which is a function of ratio of the traction or pull to the drivingtorque.

, When the propeller moves in a frontward direction, cams, such as '7, engaging rollers 8 secured to frame 4, cause sleeves 9 and 9a to rotate in opposite directions but through equal angles according to a given law which is materializedby their outline. Said law may be so chosen for instance as to cause the engine to give its full power for the chief conditions of .working (fixed point, climb, horizontal flight, ceiling) Each blade, 11 or 11a, is screwed on its sleeve 9 or 9a; whichis provided with a prolonged part 13 or 13a. Each sleeve 9 or 9a and each corresponding prolonged part 13 or 13a are made integral with one another through tenons 14, 15 or 14a, 15a provided in each of them, cotters' (which are not shown in the drawings) and a conical nut 16 or-16. The continuous beam thus formedis adapted to rotate in an outer bearing 17 or 17a and an inner bearing 18 or 18a which serve to secure the blade in the propeller casing 5. i It will be seen that the outer bearing of one blade is located on the same side of the driving shaft as the inner bearing of the other blade, and

in particular that said two bearings are located in the same plane. It is possible, with this arrangement to obtain a maximum spacing of the The sleeve 9 or 9a of the blades interengage one into the other, said sleevesbeing provided with teeth 10 or 10a and with intermediate aper- Fig. 3. The teeth 10 of the sleeve 9 pass through theapertures of the sleeve 9a and vice-versa pass through The thrust piece may comprise balls or preferably the teeth 10a of the sleeve 9a the apertures of the sleeve 9. This arrangement results in that the centrifugal within the limits of rotation for which they are provided. A weight29 fitted in prolonged part 13, serves to balance blade 11 and its sleeve 9.

Vice-versa a weight 29a. fitted in prolonged part 13a, serves to balance bladella and its sleeve 9a.

Fig. 2 and also Figs. 4 and 5 make it possible to fully understand the operation of the means for automatically compensating for the centrifugal torque of the blades. Said torque results from the obliquity, with respect to the axis of revolution of the blades, of the elementary centrifugal efforts which are exerted on either side of said axis. The sum of all these efforts may be reduced to a force parallel to the axis of revolution of the blade, and 'which is absorbed by the thrust piece, and a torque which tends to reduce the pitch, and which, within the limits of utilization, varies in the same direction as the pitch.

Fig. 4 a diagrammatic perspective view, partly in section on the line 1-1 of Fig. 1 of the mechanism fitted in the upper sleeve. lar balancing mass 25, which is adapted to slide within sleeve 9,is guided by means of two rollers 21 and 22v carried by an axis 26 integral with the sleeve. Said mass is also operatively connected to theprolonged part 13a of the sleeve 9a of the opposite blade 1111' by two rollers 23 and 24 engaging two slots such as 27 provided in said annular mass 25. It will readily be seen that the position of each balancing mass and its distance from the axis of rotation is, accordingly, a function of the angular position of the tWOLbIadES. On the other hand, the centrifugal force which acts upon said balancing mass 25 is imparted to roller 23 along line Fc (Fig. 5) and pushes it obliquely. The resultant, which is at right angles to the edge of the slot, mayin turn be split up into two forces, one Fc directly opposite to the centrifugal force acting upon the lower blade and which is therefore'to be subtracted therefrom,- and the other Ta (tangential force) which pro-' duces a couple opposed to the half centrifugal couple of said blade. The reaction ofthe couple is directed along T1' and is imparted to the upper blade through the medium of roller 21, :I'he complementary controlling device shown'by way of example in the accompanying drawings'comprises two arms such, as 30 (Figs. 1 and 2) which transmit the axial displacement of easing 5 to a sleeve 31 adapted to slide along the driving shaft. 'A groove provided in said sleeveacts through a (fork 32 upon a system of rods 33' leading to the pilot's cockpit. It will be readily understood that, to any displacementof the hub will correspond a proportional displacement of the rods so that the pilot 'will be able to see on a diaL'by means of a cursor or through any other means, what is the positionof equilibrium of the propeller blades and consequently. their pitch. Said systemiof transmission through rigid means further enables the'pilot, by exerting an effort in a direction opposite to that of the displacement produced by the mechanism, to correct the working of said mechanism so as to obtain the best possible position'of equilibrium. The pilot may also, by acting in the same direction as the mechanism, complete and improve the automatic action of said mechanism.

The annulocated in the same plane, a support But on either side of the position of equilibrium,

the effort to' be exerted increases suificiently Fig. 2, in the gear, said device comprising for instance tenons 34 and 34a respectively provided on the fork 32 and the lever 33a pivotally connected to the rod 33. The play provided between the tenons 34 and 34a corresponds for instance to the whole stroke of the hub, but the pilot is however capable of knowing the position of equilibrium and of modifying said position by merely taking up the play in one direction or the opposite one.

While I have disclosed what I deem to be a preferred embodiment of my invention it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement disposition and form of the parts without departing from the principle of my invention as comprehended within the scope of the appended claims.

What I claim is:

1. In a device for automatically regulating the pitch of a propeller, a driving shaft, a hub slidably and rotatably mounted on said shaft, at least one connecting rod between said shaft and said hub for transmitting the stresses from one to the other, at least two propeller blades, at right angles to said shaft' journalled in said hub in line with each other on either side of the axis of said shaft, two bearings in said hub for rotatably supporting each propeller blade about an axis at right angles to said shaft, said two bearings being disposed on either side of the axis of said shaft respectively, a support rigidly fixedly to said shaft, a roller carried by said support, and a cam carried by each of said propeller blades adapted to cooperate with said rollerfor adjusting the pitch of said blade according to the position of said hub on the axis of the driving shaft.

2. In a device for automatically regulating the pitch of a propeller, a driving shaft, a hub slidably and rotatably mounted on said shaft, at least one connecting a rod. between said shaft and said hub for transmitting stresses from one to the other, at least two propeller blades at right angles to said shaft journalled in said hub in line with each other on either side of the axis of said shaft, two bearings in said hub for rotatably supporting each propeller blade about an axis at right angles to said shaft, said.

'two bearings being disposed onopposite sides of the axis of the driving shaft respectively, the two bearings disposed on the same side of .the axis of said driving shaft, and which therefore correspond to opposite blades respectively, being rigidly fixed to said shaft, a roller carried by said support, and a cam carried by each of said propeller blades adapted to cooperate with said roller for adjusting the pitch of said blade according to the position of said hub on the axis of said driving shaft.

3. In a device for, automatically regulating the pitch of a propeller, a driving shaft, a hub slid- 'each other, tyvo tubular elements ably and rotatably mounted on said shaft, at least one connecting rod between said driving shaft and said hub for transmitting stresses from one to the other, at least two propeller blades at right angles to said shaft disposed in line with for supporting said propeller blades respectively, said two tubular elements extending into each other beyond the axis of the driving shaft, two bearings for rotatably supporting each propeller blade about an axis at right angles to said shaft, one of said bearings being disposed between the corresponding tubular element and the hub and the'other one between the lastmentioned tubular element and the other tubular element, said two bearings 4. In a device for automatically regulating thepitch of a propeller, a driving shaft, a hub slidably and rotatably mounted on saidshaft, at least one connecting rod between said ,driving shaft and said hub for transmitting stresses from one to the other, at least two propeller blades at right angles to said shaft disposed in line with each other, two tubular elements for supporting cording to the position of said hub along the said propeller blades respectively, said twotubular elements extending into each other beyond the axis of the driving shaft, two bearings for rotatably supporting each propeller blade about an axis at right angles to said shaft, one of said bearings being disposed between the corresponding tubular element and the hub and the other one between the last mentioned tubular element *and the other tubular element, said two bearings being disposed on opposite sides of the axis of the driving shaft respectively, the two bearings disposed onthe same side of the axis of said driving shaft, and which therefore correspond to opposite blades respectively being located in the same plane coaxially with each other, a support rigidly secured to said shaft, a roller carried by said support, and a cam carried by each .of said propeller blades adapted to cooperate with said roller-for adjusting the pitch of said blade acaxis of said driving shaft;

5. In a device for regulating the pitch of a propeller, a driving shaft, a hub casing slidably and rotatably mounted on said shaft, two rods each interposed between said driving shaft and said hub casing, two coaxial tubular parts on said hub casing extending on either side of the driving shaft at right angles thereto, two sleeves disposed in said tubular parts in coaxial. relation therewith on either side of the axis of the driving shaft, two prolonged tubular pieces of smaller diameter rigidly secured to said sleeves respectively, each prolonged tubular part ex tending on the opposite side of the axis of the driving shaft from the sleeve to which it is secured into the other sleeve, two propeller blades.

rigidly secured to the outer ends of said sleeves respectively, two bearings interposed between the tubular parts of the hub casing and the corresponding sleeves respectively, said bearings being disposed at equal distances from the axis of the driving shaft, two other bearings each interposed between one prolonged tubular piece and the sleeve corresponding to the opposite blade respectively, the two last mentioned bearings being disposed in the same planes as the two first mentioned bearings respectively, a support rigidly secured to said driving shaft, a roller carried bysaid support and a cam carried by each of said propeller blades for adjusting the 'pitch of said blade according to the position of said hub along the axis of said driving shaft.

6. In a device for regulating the pitch of a propeller having a driving shaft, a hub on said driving shaft, two propeller blades disposed in line with each other and adapted to be driven from said hub, and means for varying simultaneously the pitch of the propeller blades; the combination of two tubular elements interengaging into each other for supporting said propeller blades respectively, each of said elements passing through the other element and having a prolonged part projecting into said other element beyond the axis of the driving shaft, two bearings for supporting each propeller blade, one of said bearings being disposed between the corresponding tubular element and the hub and the other between each tubular element and theprolonged part of the other tubular element, said two bearings being disposed on opposite sides of the axis of the driving shaft respectively and a thrust bearing located on the axis of the driving shaft, interposed between the prolonged parts of said two tubular elements.

'7. In a device for regulating the pitch of a propeller having a driving shaft, a hub on said driving shaft, two propeller blades disposed in line with each other and adapted to be driven from said hub, and means for varying simultaneously the pitch of the propeller blades; the combination of two tubular elements interengaging into each other for supporting said propeller blades respectively, each of said elements passing through the other elements and having a prolonged part projecting into said other element beyond the axis of the driving shaft', a weight mounted on the end of each prolonged part remote from the corresponding blade for compensating the centrifugal strains of said blade, two bearings for supporting each propeller blade, one of said bearings being disposed between the corresponding tubular element and the hub and the other between the last mentioned tubular element and the other tubular element, said two bearings being disposed on opposite sides of the axis of the driving shaft respectively and a thrust bearing located on the axis 'of the driving shaft, interposed between the prolonged parts of said two tubular elements.

8. A device regulating the pitch of a propeller according to claim 6 further comprising an annular compensating member disposed between each tubular element and the prolonged part corresponding to the other tubular element, said annular compensating member being adapted to slide longitudinally inside the first mentioned tubular element without rotating therein, and means for,.op'eratively connecting said annular compensating member to said prolonged part in such manner that a radial displacement of said annular compensating member may correspond to an angular relative displacement of said mem- 145 her and of said prolonged part.

Louis BREGUET.

use 

